Ventilator-associated pneumonia is characterized by excessive release of neutrophil proteases in the lung.

BACKGROUND: Ventilator-associated pneumonia (VAP) is characterized by neutrophils infiltrating the alveolar space. VAP is associated with high mortality, and accurate diagnosis remains difficult. We hypothesized that proteolytic enzymes from neutrophils would be significantly increased and locally produced inhibitors of human neutrophil elastase (HNE) would be decreased in BAL fluid (BALF) from patients with confirmed VAP. We postulated that in suspected VAP, neutrophil proteases in BALF may help identify "true" VAP. METHODS: BAL was performed in 55 patients with suspected VAP and in 18 control subjects. Isolation of a pathogen(s) at > 104 colony-forming units/mL of BALF dichotomized patients into VAP (n = 12) and non-VAP (n = 43) groups. Matrix metalloproteinases (MMPs), HNE, inhibitors of HNE, and tissue inhibitors of matrix metalloproteinases (TIMPs) were quantified. Plasminogen activator (PA) activity was estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and zymography. RESULTS: Neutrophil-derived proteases HNE, MMP-8, and MMP-9 were significantly increased in cell-free BALF from patients with VAP as compared with those without VAP (median values: HNE, 2,708 ng/mL vs 294 ng/mL, P < .01; MMP-8, 184 ng/mL vs 5 ng/mL, P < .01; MMP-9, 310 ng/mL vs 11 ng/mL, P < .01). HNE activity was also significantly increased in VAP (0.45 vs 0.01 arbitrary units; P < .05). In contrast, no significant differences were observed for protease inhibitors, TIMPs, or PAs. HNE in BALF, at a cutoff of 670 ng/mL, identified VAP with a sensitivity of 93% and specificity of 79%. CONCLUSIONS: Neutrophil proteases are significantly elevated in the alveolar space in VAP and may contribute to pathogenesis. Neutrophil proteases appear to have potential in suspected VAP for distinguishing true cases from "non-VAP" cases.

A role for the fibrinolytic system in postsurgical adhesion formation.

OBJECTIVE: To look for evidence of a fibrinolytic insufficiency as a cause of adhesion formation. DESIGN: Retrospective and prospective study. SETTING: University medical center. PATIENT(S): Retrospective study: 50 patients undergoing laparoscopy, divided into patients with and without endometriosis. Prospective study: 18 patients undergoing infertility surgery involving a second-look laparoscopy. INTERVENTION(S): During all surgical procedures, adhesions were scored, and peritoneal fluid and plasma were collected. MAIN OUTCOME MEASURE(S): Parameters of the fibrinolytic system were measured to establish a possible relation with the presence and formation of adhesions. RESULT(S): In patients with endometriosis and adhesions, significantly higher peritoneal fluid concentrations were found for plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA), and plasminogen, compared with patients with endometriosis but without adhesions. In the prospective study, initial peritoneal PAI-1 concentrations correlated significantly with the extent of adhesion formation (r(s) = 0.49) and adhesion-improvement scores (r(s) = -0.52). Also, the change in concentration of tPA and fibrinogen from the initial surgical procedure to the second-look laparoscopy correlated significantly with adhesion-improvement scores (DeltatPA: r(s)= 0.50; Deltafibrinogen: r(s) = -0.64). CONCLUSION(S): This first prospective study in humans adds further weight to the hypothesis that adhesions are caused by an insufficiency in peritoneal fibrinolytic activity. Plasminogen activator inhibitor-1 is a potential marker for the identification of patients at risk for developing adhesions.

Candida albicans binds human plasminogen: identification of eight plasminogen-binding proteins.

Several microbial pathogens augment their invasive potential by binding and activating human plasminogen to generate the proteolytic enzyme plasmin. Yeast cells and cell wall proteins (CWP) of the human pathogenic fungus Candida albicans bound plasminogen with a K(d) of 70 +/- 11 nM and 112 +/- 20 nM respectively. Bound plasminogen could be activated to plasmin by mammalian plasminogen activators; no C. albicans plasminogen activator was detected. Binding of plasminogen to CWP and whole cells was inhibited by epsilon ACA, indicating that binding was predominantly to lysine residues. Candida albicans mutant strains defective in protein glycosylation did not show altered plasminogen binding, suggesting that binding was not mediated via a surface lectin. Binding was sensitive to digestion by basic carboxypeptidase, implicating C-terminal lysine residues in binding. Proteomic analysis identified eight major plasminogen-binding proteins in isolated CWP. Five of these (phosphoglycerate mutase, alcohol dehydrogenase, thioredoxin peroxidase, catalase, transcription elongation factor) had C-terminal lysine residues and three (glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase and fructose bisphosphate aldolase) did not. Activation of plasminogen could potentially increase the capacity of this pathogenic fungus for tissue invasion and necrosis. Although surface-bound plasmin(ogen) degraded fibrin, no direct evidence for a role in invasion of endothelial matrix or in penetration and damage of endothelial cells was found.